PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 215 
Genus PSEUDOLINGULA Mickwitz, 1909 
PSEUDOLINGULA AQUILINA Sinclair 
Pseudolingula aquilina StncLatr, Trans. Roy. Soc. Canada, ser. 3, vol. 39, sec. 4, p. 60, pl. 1, 
fig. 12, 1945. 
Type.—Holotype: G.S.C. 1160. 
Horizon and locality—Age uncertain; “either pre-Lowville Black River or 
Chazy”; in green siliceous limestone 25 feet from the base of the Ordovician 
section at a cliff halfway between Malbai and Cap a l’Aigle, Murray Bay, Quebec, 
Canada. 
PSEUDOLINGULA ? EVA (Billings) 
Lingula eva Bittincs, Canadian Nat. Geol., vol. 6, p. 150, 1861—Br1Lt1ncs in Logan, Geol. 
Canada, p. 141, fig. 73, 1863. 
Pseudolingula ? eva (Billings) Srnciatr, Trans. Roy. Soc. Canada, ser. 3, vol. 39, sec. 4, 
p. 60, pl. 1, figs. 16, 17, 1945. 
Lingulasma eva (Billings) Witson, Geol. Surv. Canada, Bull. 8, p. 21, pl. 1, figs. 21-23, 1946. 
Types——Lectotype: (G. W. Sinclair, 1945) G.S.C. 1160a; paratype: G.S.C. 
1160b. 
Horizon and locality—Black River ? formation, Murray Bay, Quebec, Canada. 
Discussion —This species was recently discussed by Sinclair and Wilson. 
These authors assign it to different genera. Wilson’s remarks do not indicate 
that the ornamentation of the holotype is like that of Lingulasma. No mention 
is made of the beaded exterior so characteristic of that genus and the figures of 
the type show only strong concentric undulations. A third specimen (G.S.C. 
6325), assigned by Miss Wilson to this series, is by its ornamentation definitely 
an example of Lingulasma. It is doubtful, however, that it belongs to the species 
to which it is assigned. 
PSEUDOLINGULA ? IMPERFECTA Cooper, new species 
Plate 5, D, figures 9-11; plate 6, E, figures 18-22 
Shell large for an Ordovician member of the genus, thin in substance, usually 
light lustrous bluish gray to horn brown in color. Strongly and subequally bicon- 
vex in anterior and lateral profiles, subelliptical to oval in outline. Posterolateral 
margins widely divergent, nearly straight, forming somewhat narrow shoulders 
where joining the lateral margins. Lateral margins very gently convex, sub- 
parallel, abruptly joining the somewhat strongly convex anterior margin. Sur- 
face marked by broad concentric undulations on the median portion of both 
valves but narrowly convex and closely crowded on the lateral slopes. Orna- 
mentation on lateral slopes often gently wavy and some of the lines discontinu- 
ous and irregular in direction. 
Pedicle valve with imperfect beak in all specimens examined. Brachial valve 
with thickened and inflected posterior margin; beak protruding beyond the 
posterior margin. 
Measurements in mm.—Holotype, length 22.8+, width 19.6, thickness 8.2. 
